HIV Basics

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HIV Basics

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1. What is HIV?
2. What is HIV Disease?
3. What does AIDS stand for?
4. How does HIV cause illnesses?
5. HIV transmission
6. HIV transmission routes

What is HIV?

Human - because the virus can only infect human beings. Although similar diseases exist in other animals, such as monkeys and cats, those viruses cannot infect humans nor can HIV infect other animals.

Immunodeficiency - because the virus creates a deficiency with the body's immune system, causing it to fail to work properly.

Virus - because the organism is a virus which is incapable of reproducing by itself; it must use a human cell to reproduce.

HIV (Human Immunodeficiency Virus) is a virus that affects certain white blood cells—CD4 T cells—that manage human immune system responses. When these blood cells are damaged, it becomes difficult for people to fight off infections or diseases. This condition is called "HIV disease."

What is HIV disease?

We tend to think of "disease" in simple terms: infection equals illness. It's a little different with HIV since the virus can cause slow, subtle damage to the immune system long before an infected person will feel ill. Most health care providers use the term "HIV disease" to identify the variety of changes a person may experience, from initial infection to more advanced stages of serious, life-threatening illness. The term describes the medical condition of anyone infected with the virus, regardless of his or her symptoms.

What does AIDS stand for?

Acquired - because HIV is not a condition passed on genetically; a person has to become infected with it.

Immune - because the immune system's ability to fight off viruses and bacteria becomes much less effective.

Deficiency - because the immune system fails to work properly.

Syndrome - because there is a wide range of diseases and infections a person may experience. When HIV disease was first recognized in the early 1980s, it was called AIDS. Today, the term "HIV disease" is a more accurate description of the condition. However, AIDS still used, primarily for the purpose of counting infections and as a description for advanced-stages of HIV disease. AIDS refers to individuals who have particular "AIDS-defining" conditions such as a very low CD4 white blood cell or specific illnesses.

How does HIV cause illnesses?

HIV reproduces continuously in the body from the first day of infection. A person who is infected with HIV will typically produce about 10 billion new HIV particles each day, and about 2 billion virus-fighting immune system cells (CD4 T cells- are produced and destroyed).

A person's immune system attacks HIV soon after infection, and at first is able to clear a large amount of virus from the body every 24 hours. However, for each virus particle cleared, at least one new one is created. The body's initial, vigorous anti-HIV response creates a temporary equilibrium between immune cells and the virus that may last for months or years.

Typically, a person will show no outward signs of illness during this time, except for severe flu-like symptoms after the initial infection as a sign that the immune system is kicking-in to fight off HIV.

Over time, however, the virus gains the upper hand. The amount of HIV in the body (viral load) increases and the CD4 T cell count declines.

The immune system cannot work properly under constant attack from HIV. Eventually, the virus overwhelms the defenses of the immune system, which then can no longer ward off other illness-causing infections, some of which can be life threatening.

HIV Transmission

HIV Must Be Present—Infection may only occur if one of the persons involved in an exposure situation is infected with HIV. Some people assume that certain behaviors or exposure situations can cause HIV disease, even if the virus is not present. This is not true.

There Needs to Be Enough Virus—The concentration of HIV determines whether infection will occur. In blood, for example, the virus is very concentrated. A small amount of blood is enough to infect someone. Also, the concentration of virus in blood or other fluids can change, in the same person, over time.

HIV Must Get into the Bloodstream—It is not enough to be in contact with an infected fluid for HIV to be transmitted. Healthy, intact skin does not allow HIV to get into the body.

HIV can enter through an open cut or sore, or through contact with the mucous membranes. Transmission risk is very high when HIV comes in contact with the more porous mucous membranes in the genitals, the anus, and the rectum, which are inefficient barriers to HIV. Transmission is also possible through oral sex because body fluids can enter the bloodstream through cuts in the mouth.

Paths of Infection—HIV can be transmitted through:

Unprotected vaginal, anal and oral sex
Direct blood contact, which may occur through needle sharing, transfusions, accidents in health care settings, or certain blood products
Mother to baby; before or during birth or through breast milk

Infectious Fluids—HIV can be transmitted from an infected person to another through:

Blood Semen (including pre-seminal fluid)
Vaginal secretions HIV can also be transmitted through the following bodily secretions, in limited circumstances where there is exposure to large quantities
Breast milk-expressed through feeding

Non-Infectious Fluids

Saliva-is NOT considered to be infectious. The only time saliva would pose a risk would be if it had blood present in it. There are no documented cases of HIV transmission through saliva. There is a protein in the mouth that attaches itself to the surface of blood cells and blocks infection by HIV that appears to be present in the mucous membrane in the mouth at a level sufficient enough to reduce the concentration of HIV in saliva to non-infectious levels.
Urine and Tears - are NOT considered infectious. While HIV has been found in urine and tears, it is not concentrated in an amount sufficient for transmission.
Sweat, Feces, Vomit - are NOT considered infectious. HIV has never been found in these materials. The only possible risk would be if there was blood present.

HIV Transmission Routes

HIV can enter the body through open cuts or sores and by directly infecting cells in the mucous membranes.

Transmission can happen in the mouth, the eyes, vagina, penis (through the urethra), in the anus and rectum. HIV cannot cross healthy, unbroken skin.

Sexual Transmission
HIV can be transmitted through sexual intercourse, both vaginal and anal. HIV can easily pass through the mucus membranes in the genitals and the rectum, or may pass through cuts and sores.

HIV can also be transmitted through oral sex. Conditions such as bleeding gums and poor oral health increase the risk of transmission and through oral sex.

Non-sexual Transmission
HIV can be transmitted by contact between infectious fluids and bleeding cuts or open sores in the skin. However, healthy, intact skin does not allow HIV to enter the body, and provides an excellent barrier against the virus.

Sharing Needles—Sharing syringes [needles, works or fits] to inject medicines, hormones, steroids or illegal drugs can pass blood directly from one person's blood stream to another's. It is also a very efficient way to transmit HIV and other blood borne viruses such as Hepatitis B (HBV) and Hepatitis C (HCV).

Tattoos and Piercing—There have been NO documented cases of transmission of HIV by piercing or tattooing. However, there are documented cases of Hepatitis B (HBV) through these routes. Since Hepatitis B and HIV are transmitted by the same activities, there may be a possibility of HIV transmission through tattoos and piercing.

Blood Transfusions—Since March 1985, all blood in the United States has been screened for HIV using the HIV antibody test. This practice has almost eliminated the risk of getting HIV through a blood transfusion in the United States.

Hemophiliacs—Since March 1985, all blood in the United States has been screened for HIV with the HIV antibody test. This practice has almost eliminated the risk of getting HIV through a blood transfusion in the United States. Other Blood Products. Besides whole blood, platelets [red blood cells] have transmitted HIV.

Current blood screening should prevention infection from these products. No other blood products are suspected of transmitting HIV.

Donor Insemination—This is not a regulated industry. It is recommended that donor semen be checked for the presence of HIV. When collecting semen, donors should be tested for HIV antibodies when the sample is taken. The semen should then be frozen. The donor should then be retested three months later to avoid the risk of a "window period" effect. The semen should not be used before the procedure is completed.

Organ Donation—People who are infected with HIV are encouraged not to donate organs or tissue for transplant purposes. There were very few cases of organ or tissue transplant HIV transmission from 1985 until 1994 when new government guidelines were implemented to reduce the risk of transplant transmission. These guidelines require blood from donors be tested for various strains of HIV.

Also, the donor medical history must show no evidence of risk factors or clinical symptoms of HIV infection.

Mother to Infant Transmission—It is possible for a mother who has HIV to pass the virus to her fetus, by exposure to blood and vaginal fluids during birth, or through breast milk during feeding.

Last Updated: Tuesday, June 10, 2008
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